Thanks for the reply. I did go through your project, but couldn't really find anything related to controlling and monitoring the current status of the light in existing 2-way switch circuits. Please provide me a link or additional info, if I did miss on something.

Yes, the wall switch is connected to a relay (or contactor) with 230V (or 120 V) coil and two NO contacts (lets call C1, C2). So your wall switch will no longer drive the lamp, but only the 230V coil.

These two contacts are driven by the wall switch, C1 is connected to the Arduino. On C1 you simply apply the 5V, then your board will know the position of the wall switch. The Arduino board can so drive an its own relay (5 or 12 V coil with darlington) that drive the lamp with its contact.

Basically is your boar that drive the relay and so you know if is ON or OFF.

The 230V relay was added to give the opportunity to drive the lamp also when the board is p owered off or is broken, and the second contact is used through an additional relay in NC wiring, so when the Arduino is powered on it will cut of that circuit.

Which is your real goal?

Regards,Dario.

Souliss - Open-source Distributed Home Automation with Arduino and Android

Thanks. I had drawn a circuit diagram at a high level, just to let you know what I understood. Please let me if I got you right. I had attached the circuit diagram.

The problem I see in this circuit is that the switches wont perform until the Arduino switches itself off. In other words, if the light is switched on from arduino, the light can not be switched off from the switch.

You got it partially, instead of a classic wall switch you need something with two contacts one to the NC relay and one to the Arduino board. Since in the market the wall switches with two contacts (4 pins instead of 2 pins) are not so common a relay with 230V coil was used.

So your wall switch will act on that relay, that will transfer the open/close position of your wall switch into two dry contacts (at least one shall be rated for 230V operations). One of these two is used to power the lamp via the NC relay, so is directly connected to the 230V.The other is used to notify to the Arduino board if the wall switch is pressed or not, so is connected to the 5V and the input pin of the Arduino.

So until the Arduino will not be powered off, the NC relay broke the circuit of the NC relay, but the wall switch positions are reported to the Arduino board and so you could act on the NO relay from wall switch or other interfaces (we are using in Souliss driving also from Android and Modbus). When the Arduino is powered off, for example is broken, the wall switch only will work via the NC relay.

This scheme was used because Shine (that is the other developer of Souliss) was warried about lost completely lamps control in case of faults.

Generally, if you just care about drive the lamp from wall switch or other interfaces going through Arduino, simpli connect the wall switch to the board and the Arduino to the lamp via relay. In that case, if Arduino fails your lights will stay off.

Regards,Dario.

Souliss - Open-source Distributed Home Automation with Arduino and Android

I don't have an idea on the switch with 4 pins. I understand that the switch comes with two pairs of contacts. One pair of contacts is connected to a 230V supply while the other pair of contacts is connected to a 5V supply.

The 230V supply is used to control the lamp using the NC Relay when the arduino is switched off.

When the arduino is powered on, the 5V supply reports the position of the switch to the Arduino from where the actions over the lamp are controlled.

The one in the link that I've included before is at 12 euros that is mostly the lowest that you can found, the price are related to the contact rate. The contactors are relays, is a just a different name used to indicate devices that has 230V coil rather relays are typically at lower voltages.

If you have a lot of lamps to control and don't want to spend too much money, you can always connect the wall switch to the arduino directly and let it control the lamp, and maybe use the scheme that I've proposed only for some main lights.

A middle way is changing your wall switch with double poles one, they are cheaper a smaller than a contactor and has two poles. These are think for breaking both phase and neutral to a device and are not common for light, rather are used for high power devices.

In that case, you have the switch and two poles, so you can use the same scheme without the contactor in between.

Regards,Dario.

Souliss - Open-source Distributed Home Automation with Arduino and Android

I considered the double throw relay as a possible solution to knowing the state of a latching relay until I saw the cost. When you spend as much on a relay as the rest of the circuitry, it gets a little silly. That's why I've been researching how to sense that current is flowing in combination with voltage being available.

What I want to do is power the electronics of a switch with the power that's available in the switch box (no batteries or separate power supply) This means that I have to have a tiny power supply that takes mains voltage (110 for me) and gives me 5V to run the circuitry. On a multi-switch setup, where there are both SPDT and DPDT switches in the chain, finding power and knowing the state of the latching relay can become quite a task without rewiring the switches.

I considered the double throw relay as a possible solution to knowing the state of a latching relay until I saw the cost. When you spend as much on a relay as the rest of the circuitry, it gets a little silly. That's why I've been researching how to sense that current is flowing in combination with voltage being available.

What I want to do is power the electronics of a switch with the power that's available in the switch box (no batteries or separate power supply) This means that I have to have a tiny power supply that takes mains voltage (110 for me) and gives me 5V to run the circuitry. On a multi-switch setup, where there are both SPDT and DPDT switches in the chain, finding power and knowing the state of the latching relay can become quite a task without rewiring the switches.

If this is your job, the cheapest solution is a double pole wall switch (7 $) and no additional space or power supply required as the one that I've linked before.

If you want to sense the 110V you have to build a capacitive transformer, but it will require an isolation, otherwise you may risk to burn your board.

Regards,Dario.

Souliss - Open-source Distributed Home Automation with Arduino and Android

Thanks for the reply. I did go through your project, but couldn't really find anything related to controlling and monitoring the current status of the light in existing 2-way switch circuits. Please provide me a link or additional info, if I did miss on something.

Hello everybody.

I am sorry. I have not read the forum for some days and I was not able to answer.

Anyway, I can explain the concept of the schematic and its aim. The basic concept is to make a "3 relays circuit". First relay to change between manual and remote mode, second one to let pass the current from the fase cable, and the third one works as "inversal" relay, detecting the change of state of the switch connected to the fase cable.

Why to use this concept? Ok. For me it was essential two things:

1- manual mode has preference over remote mode, so if the state of the switch is changed, by internal programming at Arduino board, the remote mode is always disconnected (this can be changed for emergency modes, as it is controlled by Arduino)

2- If the PCB has a problem and it does not work, all the PCBs are a cable. The current will arrive directly from the fase cable that it pass through the switch. It always work in manual mode. Without current at relays the only way to work is manual mode.

im not sure if your question has been answered, so ill just cut to the chase...

you can set your relay like a 3 way switch. NC and NO of the relay will serve as the traveler leads, with the C as the common. Therefore, you will need a 4 way switch between your relay and a 3 way switch. This will allow your to control your lights from 3+ locations simultaneously.